/**
 * Software License, Version 1.0
 * 
 * Copyright 2003 The Trustees of Indiana University.  All rights reserved.
 * 
 *
 *Redistribution and use in source and binary forms, with or without 
 *modification, are permitted provided that the following conditions are met:
 *
 *1) All redistributions of source code must retain the above copyright notice,
 * the list of authors in the original source code, this list of conditions and
 * the disclaimer listed in this license;
 *2) All redistributions in binary form must reproduce the above copyright 
 * notice, this list of conditions and the disclaimer listed in this license in
 * the documentation and/or other materials provided with the distribution;
 *3) Any documentation included with all redistributions must include the 
 * following acknowledgement:
 *
 *"This product includes software developed by the Community Grids Lab. For 
 * further information contact the Community Grids Lab at 
 * http://communitygrids.iu.edu/."
 *
 * Alternatively, this acknowledgement may appear in the software itself, and 
 * wherever such third-party acknowledgments normally appear.
 * 
 *4) The name Indiana University or Community Grids Lab or NaradaBrokering, 
 * shall not be used to endorse or promote products derived from this software 
 * without prior written permission from Indiana University.  For written 
 * permission, please contact the Advanced Research and Technology Institute 
 * ("ARTI") at 351 West 10th Street, Indianapolis, Indiana 46202.
 *5) Products derived from this software may not be called NaradaBrokering, 
 * nor may Indiana University or Community Grids Lab or NaradaBrokering appear
 * in their name, without prior written permission of ARTI.
 * 
 *
 * Indiana University provides no reassurances that the source code provided 
 * does not infringe the patent or any other intellectual property rights of 
 * any other entity.  Indiana University disclaims any liability to any 
 * recipient for claims brought by any other entity based on infringement of 
 * intellectual property rights or otherwise.  
 *
 *LICENSEE UNDERSTANDS THAT SOFTWARE IS PROVIDED "AS IS" FOR WHICH NO 
 *WARRANTIES AS TO CAPABILITIES OR ACCURACY ARE MADE. INDIANA UNIVERSITY GIVES
 *NO WARRANTIES AND MAKES NO REPRESENTATION THAT SOFTWARE IS FREE OF 
 *INFRINGEMENT OF THIRD PARTY PATENT, COPYRIGHT, OR OTHER PROPRIETARY RIGHTS. 
 *INDIANA UNIVERSITY MAKES NO WARRANTIES THAT SOFTWARE IS FREE FROM "BUGS", 
 *"VIRUSES", "TROJAN HORSES", "TRAP DOORS", "WORMS", OR OTHER HARMFUL CODE.  
 *LICENSEE ASSUMES THE ENTIRE RISK AS TO THE PERFORMANCE OF SOFTWARE AND/OR 
 *ASSOCIATED MATERIALS, AND TO THE PERFORMANCE AND VALIDITY OF INFORMATION 
 *GENERATED USING SOFTWARE.
 */
package cgl.narada.wsinfra.wse.matching;


import java.util.Enumeration;
import java.util.Hashtable;

/** Manages the list of subscriptions available at node.

    @author Shrideep Pallickara
    $Date: 2005/07/29 22:41:30 $
    $Revision: 1.4 $
*/

public class SubscriptionManagement {
  private Hashtable subscriptions;
  private String moduleName = "SubscriptionManagement: ";

  public SubscriptionManagement() {
    subscriptions = new Hashtable();
  }

  /** Checks to see if an entry based on the specified identifier exists
      within the subscription management tables. */
  public boolean hasEntry(String identifier) {
    if (identifier == null) {
      return false;
    }
    boolean hasEntry = subscriptions.containsKey(identifier);
    return hasEntry;
  }


  /** Gets the entry corresponding to the specified identifier. This method
      will return a NULL iff
      <li> The entry is not present within the subscription tables.
      <li> The specified Identifier is NULL */
  public SubscriptionEntry getEntry(String identifier) {
    if (identifier == null) {
      return null;
    }
    
    Object entry = subscriptions.get(identifier);
    if (entry != null) {
      return (SubscriptionEntry) entry;
    }
    
    return null;
  }


  
  /** Deletes the entry corresponding to the specified identifier. This method
      will return a NULL iff
      <li> The entry is not present within the subscription tables.
      <li> The specified Identifier is NULL
      If successful the OLD entry is returned. */
  public SubscriptionEntry deleteEntry(String identifier) {
    if (identifier == null) {
      return null;
    }
    
    Object entry = subscriptions.remove(identifier);
    if (entry != null) {
      System.out.println(moduleName + "Deleted entry corresponding to [" +
			 identifier + "]");
      return (SubscriptionEntry) entry;
    }
    
    return null;
  }

  
  /** Updates the entry corresponding to the specified identifier. This method
      will return a NULL iff 
      <li> The entry is not present within the subscription tables.
      <li> The specified Identifier is NULL
      <li> The updatedEntry is NULL
      If successful the OLD entry is returned. */
  public SubscriptionEntry updateEntry(SubscriptionEntry updatedEntry) {
    if (updatedEntry == null) {
      System.out.println(moduleName + "The updatedEntry is NULL!");
      return null;
    }
    
    String identifier = updatedEntry.getIdentifier();
    //subscriptions.remove(identifier);
    Object entry = subscriptions.put(identifier, updatedEntry);
    
    if (entry != null) {
      System.out.println(moduleName + "Updated the subscriptionEntry");
      return (SubscriptionEntry) entry;
    }
    
    return null;
  }
  
  
  /** Gets the entry corresponding to the specified identifier. This method
      will return a NULL iff
      <li> An entry is already present within the subscription tables.
      <li> The specified Identifier is NULL
      <li> The addEntry is NULL
      <li> There is already an entry corresponding to the identifier contained
      in addEntry
      If successful the NEWLY added entry is returned. */
  public SubscriptionEntry addEntry(SubscriptionEntry addEntry) {
    System.out.println(moduleName + "Adding entry ..");
    if (addEntry == null) {
      System.out.println(moduleName + "Trying to add a NULL entry.");
      return null;
    }

    String identifier = addEntry.getIdentifier();
    if (identifier == null) {
      System.out.println(moduleName + "The identifier is NULL.");
      return null;
    }

    
    if (subscriptions.containsKey(identifier)) {
      System.out.println(moduleName + "We already know about this identifier");
      return null;
    }
    
    subscriptions.put(identifier, addEntry);
    System.out.println(moduleName + "Added subscription entry corresponding" +
		       " to [" + identifier + "]");
    return addEntry; 
  }
  
  
  /** Gets the list of subscriptions that are managed. This is returned as an
      enumeration. */
  public Enumeration getSubscriptionIdentifiers() {
    if (subscriptions == null) {
      return null;
    }

    return subscriptions.keys();
  }

}
